Connector-plug part for an optical plug-in connection, method for connecting a connector-plug part to the end of an optical waveguide cable and device for carrying out said method

ABSTRACT

In order to advantageously weld a pre-mounted connector-plug ( 1 ) to an optical waveguide cable, the connector-plug part is provided with a pin holder ( 4 ) receiving a connector-plug pin ( 2 ) on a pin receiving section ( 5 ). Preferably, two cladding parts ( 8, 8 ′) form a cable receiving section ( 6 ) in said pin holder. In order to carry out welding in a simple manner on the bare end ( 22 ) of the end of a fiber, the cladding parts ( 8, 8 ′) can be pivoted around a hinge ( 9, 9 ′) between an open position and a closed position.

The invention relates to a connector-plug part for an optical plug-inconnection according to the precharacterizing clause of claim 1. As isevident, the main task of the connector-plug part is that of ensuring atension-resistant connection between the connector-plug pin and theoptical waveguide cable. At the same time, assembly should also bepossible under conditions in the field.

There are in principle two possible ways in which an optical waveguidecable is connected to a connector-plug part. The optical waveguide cablemay already be prefabricated with the connector-plug part at the factoryas what is known as a pigtail, so that finally the end of the pigtail tobe connected to a power supply system by a welded connection.Alternatively, however, it is also possible for just a fiber stub to beinserted into the connector-plug pin at the factory, the welding to theoptical waveguide cable taking place directly at the connector-plugpart. Connector-plug parts suitable for the latter method are describedfor example in WO 96/31795 or in EP 864 888. For attaching the weldingelectrodes, special openings or clearances are provided.

A disadvantage of the known welding technique at the fiber stub is thatthe welded location itself is difficult to access and that observationof the welding operation is also made more difficult. It is therefore anobject of the invention to provide a connector-plug part of the typestated at the beginning which is particularly suitable for the weldingtechnique at the fiber stub, it being possible for the welding operationitself to be carried out as unhindered as possible and with good viewingconditions. It is intended in this case that both the pre-assembly andthe final assembly of the connector-plug part can be carried out quicklyand without complex auxiliary means.

This object is achieved according to the invention by a connector-plugpart which has the features in claim 1. The connector-plug pin itselfmay in this case be pre-assembled independently of its mounting orstructure in the pin receiving section. The cladding part, which can bepivoted out at the joint, makes it possible in a particularly simple wayfor the welded location at the fiber stub to be exposed and consequentlymade accessible. In certain cases, the pivotable cladding part could,however, also be advantageous in connection with the pre-fabrication ofpigtails.

It is particularly advantageous for the entire pin holder to comprise atleast two shell parts, which can be fitted together along thelongitudinal center axis, each shell part having a pivotable claddingpart. The shell parts can be easily produced and can be closed aroundthe connector-plug pin. However, it goes without saying that it wouldalso be conceivable to form the pin holder in one piece, at least in theregion of the pin receiving section.

The pivotable cladding parts may altogether form the cable receivingsection and be connected to the pin receiving section at the joint.Alternatively, however, it would also be conceivable for the pivotablecladding part to extend only over part of the length of the cablereceiving section.

Particular advantages arise in technical production-related terms if thepin holder comprises two identical shell parts which can be fittedtogether on a plane running through the longitudinal center axis. Inthis way, different types of shell parts do not have to be produced,because the pin holder can be assembled from two identical shell parts.

For the connection of neighboring shell parts, projections andclearances which engage in one another, in particular conical lugs andlug openings, may be provided on their contacting surfaces. Depending onthe conicity chosen, the two shell parts may be joined together byslight pressure. Since the pin holder generally still has to be insertedinto a connector-plug housing, it is particularly expedient if at leastone conical section, which can be pressed into a corresponding conicalreceptacle on the connector-plug housing, is provided on the outside ofthe pin holder.

The pin holder advantageously consists of a plastic material, the jointbeing a film hinge. As is evident, the pivotable cladding part can inthis way be formed in one piece with the other parts by theinjection-molding process. Given correct choice of the plastic and givencorrect dimensioning, an adequate mechanical load-bearing capacity ofthe film hinge can be achieved without impairing the properties of thejoint.

In the case of optical plug-in connections, it is customary for theconnector-plug pin to be axially prestressed to maintain loss-free lighttransmission under various mechanical conditions. In the present case,the connector-plug pin may be mounted with limited displaceability inthe pin receiving section under axial spring prestressing.Alternatively, however, it is also conceivable for the connector-plugpin to be fixedly held in the pin receiving section and for at least oneaxially resilient region to be provided on the cable receiving section.

A comparable solution is also described for example in EP 864 888,mentioned at the beginning.

For the displaceable mounting of the connector-plug pin, it is expedientif a rib which engages in a clearance in the outer circumferentialsurface of the connector-plug pin in such a way that its resilientdisplacement is limited and that it is held in a rotationally fixedmanner is arranged on the inside of at least one shell part, in theregion of the pin receiving section. The prestressing can be achievedwith a helical compression spring which is supported in the pinreceiving section on the one hand against an abutment and on the otherhand against the rear part of the connector-plug pin.

A particularly optimal way of working for use in the field is obtainedif the connector-plug part is prepared as a pre-assembled unit forconnecting onto the end of an optical waveguide cable. In this case, anoptical waveguide stub is fastened in the connector-plug pin in such away that its stripped end on the cable side lies within the pivotingregion of the cladding part, the cladding part or the cladding partsbeing kept in an at least partly opened position. The fixing andcentering of the optical waveguide stub may take place by differentmethods that are already known per se. The linear dimensioning withinthe pivoting region of the cladding parts ensures that subsequentcutting to length does not have to be carried out during use in thefield, but that the intended welded location lies at the correct placewithin the pin holder. Complete closing of the cladding parts is notdesired, since they can only be opened again with difficulty. Thecladding parts must therefore be kept in the open position at least tothe extent that the conical lugs cannot engage. In such a position, thefiber stub would also be adequately protected. The cladding parts may,however, also already be pivoted open to the extent necessary for thelater welding process, for example by 90°, in relation to thelongitudinal center axis. In such a case, a protective cap may beprovided, protecting the protruding fiber stub and if appropriate alsokeeping the cladding parts in the open position.

The invention also relates to a method for connecting a connector-plugpart to the end of an optical waveguide cable, which method has thefeatures in claim 13. By contrast with the conventional weldingtechnique with welding inside the connector-plug pin or inside the pinholder, in the case of the method according to the invention theconductor ends to be welded can be centered very precisely in relationto each other. The attachment of the welding device takes place withoutany hindrance and the welded location can also be optimally observed.After the welding operation, the cladding parts need only be snappedtogether, a tension-resistant crimping with the cable sheath also takingplace.

After the welding, the welded location can be enclosed with a protectiveelement. This may either already be pushed onto the optical waveguidebeforehand, and is then merely also displaced axially after the welding.Alternatively, the protective element could also be formed in such a waythat it can be fitted on after the welding. In order to create space forsuch manipulations, it is expedient if, after the welding, the pinholder and the cable end are removed, in particular raised, from thecentering block in the clamped state. As is evident, a few centimetersare already sufficient for this.

Finally, the invention also relates to a device for carrying out themethod which is characterized by the features in claim 16.

The clamping of the pin holder and the cable end and the alignment in av-shaped centering groove of the ends of the optical waveguides to beconnected ensure a very precise welded connection. The clearance on thecentering block in the region of the intended welded location makes goodaccessibility and ventilation of the welded location possible. In viewof the very small lift, the lifting device for raising the clampingmeans could also be manually actuated.

Further advantages and individual features of the invention emerge fromthe description which follows of an exemplary embodiment and from thedrawings, in which:

FIG. 1 shows a perspective representation with the individual parts of aconnector-plug part before the pre-assembly,

FIG. 2 shows the connector-plug part according to FIG. 1 with insertedconnector-plug pin,

FIG. 3 shows the connector-plug part according to FIG. 2 after thepre-assembly,

FIG. 4 shows a perspective representation of a device for carrying outthe welding method in two different working positions,

FIG. 5 shows a perspective representation of a connector-plug part afterthe welding operation and before the closing of the shell parts,

FIG. 6 shows the connector-plug part according to FIG. 5 after thepre-fabrication with the cable,

FIG. 7 shows the connector-plug part according to FIG. 6 before theinsertion in a connector-plug housing and

FIG. 8 shows a perspective representation of a ready assembled connectorplug.

According to FIG. 1, a connector-plug part, designated as a whole by 1,substantially comprises a pin holder, designated as a whole by 4, and aconnector-plug pin 2 of a generally very hard material, such as ceramicor hard metal for example. The pin holder itself in turn comprises twoshell parts 10, 10′, which can be fitted together on a plane runningthrough a longitudinal center axis 3. Finally, the pin holder 4 (in theclosed state) is divided into a pin receiving section 5 and a cablereceiving section 6.

The two shell parts 10, 10′ consist for example of plastic material,preferably being injection-molded in the opened-out position fortechnical molding-related reasons. The two shell parts are completelyidentical. For the connection to each other, conical lugs 12 andcorresponding lug openings 13 are provided on the mutually contactingsurfaces 11. The hermaphroditic arrangement of these connecting meansallows the sleeve-like pin holder 4 to be produced from shell parts of asingle type.

In the case of the present exemplary embodiment, each shell part 10, 10′forms over the entire length of the cable receiving section 6 a claddingpart 8, 8′, which is connected to the pin receiving section 5 by a filmhinge 9. The cladding parts can in this case be swung outunproblematically by 90° in relation to the longitudinal center axis 3.

The connector-plug pin 2 is provided on its outer circumferentialsurface with two plane-parallel clearances 18. A pair of correspondingribs 17 on the inside of the pin receiving section 5 engage in theseclearances, a certain resilient displacement in the direction of thelongitudinal center axis 3 being allowed. A helical compression spring19 provides the necessary axial prestressing.

In the case of the exemplary embodiment according to FIG. 1, an opticalwaveguide stub 21 has already been fixedly connected to theconnector-plug pin 2, and centered in it. This stub has a bare, strippedend 22.

According to FIG. 2, the connector-plug pin 2 is placed on the shellpart 10′, into the receptacle provided for this purpose. The helicalcompression spring 90 is in this case supported against an abutment 31,so that the connector-plug pin 2 is prestressed into its outermostposition, where it is restricted by the rib 17. The abutment 31 has athrough-opening for the fiber stub 21.

According to FIG. 3, the two shell parts 10, 10′ are snapped together inthe region of the pin receiving section 5, while the two cladding parts8, 8′ are angled away by 90°, so that the fiber stub 21 is exposed. Toprotect the fiber stub, a protective cap 32 may be fitted onto it. Theentire arrangement forms a pre-assembled unit 20, as can be prepared atthe factory for use in the field.

The connection of a pre-assembled unit 20 to the end of an opticalwaveguide cable 7 is represented by FIG. 4. The device provided for thispurpose is represented in the two working positions A and B. Itsubstantially comprises a first clamping means 26 and a second clampingmeans 27, arranged at a distance from the latter. Arranged in between isa centering block 28 with a v-shaped centering groove 29. The centeringgroove is provided in the region of the intended welded location 24 witha clearance 30. This clearance makes it possible for welding electrodes33 or other suitable welding devices, such as laser heads etc., to bebrought up to the welded location.

First, the pre-assembled unit 20 is clamped in on the first clampingmeans 26. The same happens with the optical waveguide cable 7, which isfixed on the second clamping means 27. The bare conductor ends 22 and 23lie opposite each other in the v-groove 29. By activating the weldingdevice 33, fusing of the conductor ends takes place.

This is followed by simultaneous raising of the first and secondclamping means 26 and 27 by the amount of lift H into the second workingposition B. This may for example be a lift of 20 mm. As is evident, inthis raised position the welded location is moved out of the region ofthe centering groove 29 and the welding device 33. Now the weldedlocation can be covered with a protective element 25.

A unit prepared in this way is represented after the welding operationin FIG. 5. The two cladding parts 8, 8′ are now carefully pivotedtogether in the direction of the arrow x and then snapped together. Thelast operation is to apply a crimping sleeve 34 according to FIG. 6.This serves for the actual tension relief, because it transmits theforces on the outer cable cladding to the connector-plug part 1.

Also required in most cases for the handling of the optical plug-inconnection is a connector-plug housing 14, which can be made to engagein a corresponding connector-plug socket. Details of such connectorplugs are known to a person skilled in the art and are not described inany more detail here.

For the insertion of the connector-plug part 1 into the connector-plughousing 14, the pin holder 4 is provided on its outer circumferentialsurface with a conical section 15. The connector-plug part is insertedinto the connector-plug housing 14 in the direction of the arrow Y, theconical section 15 being pressed into a conical receptacle 16 in theconnector-plug housing. Also provided on the outer circumferentialsurface are positioning means 36 for the radial positioning of theconnector-plug part in the connector-plug housing 14. Finally, a kinkpreventer 35, which prevents the cable 7 from being bent with animpermissible bending radius, is fastened to the connector-plug housing.

1. A connector-plug part (1) for an optical plug-in connection, with aconnector-plug pin (2) for receiving an optical waveguide extending overa longitudinal center axis (3) and with a sleeve-like pin holder (4)with a pin receiving section (5), in which the connector-plug pin isheld, and with a cable receiving section (6), to which the end of anoptical waveguide cable (7) can be fixed in a tension-resistant manner,characterized in that the cable receiving section (6) has at least onecladding part (8), which can be pivoted at a joint (9) by a certainpivoting angle between an open position and a closed position.
 2. Theconnector-plug part as claimed in claim 1, characterized in that the pinholder (4) comprises at least two shell parts (10, 10′), which can befitted together along the longitudinal center axis (3), each shell parthaving a pivotable cladding part.
 3. The connector-plug part as claimedin claim 2, characterized in that the cladding parts altogether form thecable receiving section (6) and are connected to the pin receivingsection at the joint.
 4. The connector-plug part as claimed in claim 2,characterized in that the pin holder (4) comprises two identical shellparts (10, 10′) which can be fitted together on a plane running throughthe longitudinal center axis (3).
 5. The connector-plug part as claimedin one of claims 2, characterized in that neighboring shell parts haveon their contacting surfaces (ii) projections and clearances whichen-gage in one another, in particular conical lugs (12) and lug openings(13).
 6. The connector-plug part as claimed in one of claims 1,characterized in that, to secure the pin holder (4) in a connector-plughousing (14), at least one conical section (15), which can be pressedinto a corresponding conical receptacle (16) on the connector-plughousing, is provided on the outside of the pin holder.
 7. Theconnector-plug part as claimed in claim 1, characterized in that the pinholder consists of a plastic material and in that the joint (9) is afilm hinge.
 8. The connector-plug part as claimed in claim 1,characterized in that the connector-plug pin (2) is mounted with limiteddisplaceability in the pin receiving section (5) under axial springprestressing.
 9. The connector-plug part as claimed in claim 1,characterized in that the connector-plug pin (2) is fixedly held in thepin receiving section (5) and in that at least one axially resilientregion is provided on the cable receiving section (6).
 10. Theconnector-plug part as claimed in claim 8, characterized in that a rib(17) which engages in a clearance (18) in the outer circumferentialsurface of the connectorplug pin (2) in such a way that its resilientdisplacement is limited and that it is held in a rotationally fixedmanner is arranged on the inside of at least one shell part (10), in theregion of the pin receiving section (5).
 11. The connector-plug part asclaimed in claim 8, characterized in that the connector-plug pin (2) isprestressed in the pin receiving section (5) by means of a helicalcompression spring (19).
 12. The connector-plug part as claimed in claim1, as a pre-assembled unit (10) for connecting onto the end of anoptical waveguide cable (7), an optical waveguide stub (21) beingfastened in the connector-plug pin (2) in such way that its stripped end(22) on the cable side lies within the pivoting region of the claddingpart and the cladding part or the cladding parts being kept in an atleast partly opened position.
 13. A method for connecting aconnector-plug part (1) as claimed in one of claims 1 to 11 to the endof an optical waveguide cable (7) using a pre-assembled unit as claimedin claim 12, characterized in that the pin holder (4) and the cable endare clamped in such a way that the bare conductor end (22) of theoptical waveguide stub (21) and the bare conductor end (23) of theoptical waveguide at the cable end lie coaxially opposite each other ona centering block (28), in that the bare conductor ends are welded toeach other, in that subsequently the cladding part or the cladding partsis or are pivoted into the closed position, and in that the cable end isconnected to the cable receiving section (6) in a tension-resistantmanner.
 14. The method as claimed in claim 13, characterized in that,after the welding, the welded location is enclosed with a protectiveelement (25).
 15. The method as claimed in claim 13, characterized inthat, after the welding, the pin holder (4) and the cable end areremoved, in particular raised, from the centering block (28) in theclamped state.
 16. A device for carrying out the method as claimed inclaim 13, characterized by a first clamping means (26) for clamping inthe pin holder (4), a second clamping means (27) for clamping in thecable end, a centering block (28) with a v-shaped centering groove (29)arranged between the first and the second clamping means, the centeringblock (28) having in the region of the intended welded location (24) aclearance (30) interrupting the centering groove (29).
 17. The device asclaimed in claim 16, characterized in that the clamping means (26, 27)are provided with a lifting device for simultaneously lifting the weldedoptical waveguide off the centering block (28).